Physical random access channel procedure

Abstract

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station, a random access channel configuration that indicates one or more physical random access channel (PRACH) formats associated with antenna switching. The UE may transmit, to the base station, a PRACH sequence using a PRACH format associated with antenna switching from the one or more PRACH formats associated with antenna switching. Numerous other aspects are described.

What is claimed is: 
     
       1. An apparatus for wireless communication, comprising:
 a memory comprising instructions; and 
 one or more processors configured to execute the instructions and cause the apparatus to:
 obtain a random access channel configuration that indicates one or more physical random access channel (PRACH) formats associated with antenna switching from a first antenna to a second antenna; and 
 output for transmission a PRACH sequence using a PRACH format associated with antenna switching from the one or more PRACH formats associated with antenna switching. 
 
 
     
     
       2. The apparatus of  claim 1 , wherein the one or more processors are further configured to execute the instructions and cause the apparatus to:
 output for transmission an indication of an antenna switching capability of the apparatus. 
 
     
     
       3. The apparatus of  claim 1 , wherein the one or more processors, to output for transmission the PRACH sequence, are configured to cause the apparatus to:
 output for transmission a first one or more repetitions of the PRACH sequence using the first antenna; 
 perform, at an antenna switch time, an antenna switch procedure to switch from the first antenna to the second antenna; and 
 output for transmission a second one or more repetitions of the PRACH sequence using the second antenna. 
 
     
     
       4. The apparatus of  claim 3 , wherein the antenna switch time is included in a duration of a last repetition included in the first one or more repetitions. 
     
     
       5. The apparatus of  claim 3 , wherein the antenna switch time is based at least in part on a duration of the PRACH sequence, wherein the duration of the PRACH sequence includes a duration of each repetition associated with the PRACH sequence and a duration of a cyclic prefix included in the PRACH sequence. 
     
     
       6. The apparatus of  claim 3 , wherein the antenna switch time occurs an amount of time prior to an end of a last repetition included in the first one or more repetitions, wherein the amount of time is based at least in part on a duration of a cyclic prefix included in the PRACH sequence. 
     
     
       7. The apparatus of  claim 3 , wherein the one or more processors are further configured to execute the instructions and cause the apparatus to:
 identify the antenna switch time based at least in part on a stored configuration; or 
 obtain an indication of the antenna switch time. 
 
     
     
       8. The apparatus of  claim 1 , wherein the memory and the one or more processors, to obtain the random access channel configuration, are configured to execute the instructions and cause the apparatus to:
 obtain an indication of the PRACH format from the one or more PRACH formats, wherein the PRACH format indicates that the PRACH sequence is to include one or more repetitions and indicates that the apparatus is to perform antenna switching when outputting for transmission the PRACH sequence. 
 
     
     
       9. The apparatus of  claim 1 , wherein the one or more processors, to obtain the random access channel configuration, are configured to execute the instructions and cause the apparatus to:
 obtain an indication of the PRACH format from the one or more PRACH formats; and 
 obtain an indication of whether the apparatus is to perform antenna switching when outputting for transmission the PRACH sequence using the PRACH format. 
 
     
     
       10. The apparatus of  claim 1 , wherein the one or more processors are further configured to execute the instructions and cause the apparatus to:
 obtain an indication of a first set of random access channel occasions that are associated with antenna switching by the apparatus and a second set of random access channel occasions that are not associated with antenna switching by the apparatus; 
 obtain an indication of a random access channel occasion, included in the first set of random access channel occasions or the second set of random access channel occasions, associated with the PRACH sequence; and 
 selectively perform antenna switching when outputting for transmission the PRACH sequence based at least in part on whether the random access channel occasion is included in the first set of random access channel occasions or the second set of random access channel occasions. 
 
     
     
       11. The apparatus of  claim 1 , wherein the memory and the one or more processors, when receiving the random access channel configuration, are configured to execute the instructions and cause the apparatus to:
 obtain an indication of the PRACH format from the one or more PRACH formats, wherein the PRACH format includes one or more repetition groups and an indication that antenna switching is to be used by the apparatus when outputting for transmission the PRACH sequence, wherein each repetition group of the one or more repetition groups includes: one or more repetitions of the PRACH sequence, and a cyclic prefix. 
 
     
     
       12. The apparatus of  claim 11 , wherein the one or more processors, when receiving the indication of the PRACH format, are configured to execute the instructions and cause the apparatus to perform at least one of:
 obtain an indication that the apparatus is to perform an antenna switching procedure at an end of at least one of the one or more repetition group; or 
 obtain an indication of at least one of:
 a starting time of each repetition group included in the one or more repetition groups, wherein the starting time is based at least in part on an amount of time associated with an antenna switching capability of the apparatus, or 
 a time gap between each repetition group included in the one or more repetition groups. 
 
 
     
     
       13. The apparatus of  claim 1 , further comprising at least one transceiver configured to receive the random access channel configuration and transmit the PRACH sequence using the PRACH format, wherein the apparatus is configured as a user equipment. 
     
     
       14. A method of wireless communication performed at a user equipment (UE), comprising:
 receiving a random access channel configuration that indicates one or more physical random access channel (PRACH) formats associated with antenna switching from a first antenna of the UE to a second antenna of the UE; and 
 transmitting a PRACH sequence using a PRACH format associated with antenna switching from the one or more PRACH formats associated with antenna switching. 
 
     
     
       15. The method of  claim 14 , further comprising:
 transmitting an indication of an antenna switching capability of the UE. 
 
     
     
       16. The method of  claim 14 , wherein transmitting the PRACH sequence comprises:
 transmitting a first one or more repetitions of the PRACH sequence using the first antenna; 
 performing, at an antenna switch time, an antenna switch procedure to switch from the first antenna to the second antenna; and 
 transmitting a second one or more repetitions of the PRACH sequence using the second antenna. 
 
     
     
       17. The method of  claim 16 , wherein the antenna switch time is included in a duration of a last repetition included in the first one or more repetitions. 
     
     
       18. The method of  claim 16 , wherein the antenna switch time is based at least in part on a duration of the PRACH sequence, wherein the duration of the PRACH sequence includes a duration of each repetition associated with the PRACH sequence and a duration of a cyclic prefix included in the PRACH sequence. 
     
     
       19. The method of  claim 16 , wherein the antenna switch time occurs an amount of time prior to an end of a last repetition, in a time domain, included in the first one or more repetitions, wherein the amount of time is based at least in part on a duration of a cyclic prefix included in the PRACH sequence. 
     
     
       20. The method of  claim 16 , further comprising:
 identifying the antenna switch time based at least in part on a stored configuration; or 
 receiving an indication of the antenna switch time. 
 
     
     
       21. The method of  claim 14 , wherein receiving the random access channel configuration comprises:
 receiving an indication of the PRACH format from the one or more PRACH formats, wherein the PRACH format indicates that the PRACH sequence is to include one or more repetitions and indicates that the UE is to perform antenna switching when transmitting the PRACH sequence. 
 
     
     
       22. The method of  claim 14 , wherein receiving the random access channel configuration comprises:
 receiving an indication of the PRACH format from the one or more PRACH formats; and 
 receiving an indication of whether the UE is to perform antenna switching when transmitting the PRACH sequence using the PRACH format. 
 
     
     
       23. The method of  claim 14 , further comprising:
 receiving an indication of a first set of random access channel occasions that are associated with antenna switching by the UE and a second set of random access channel occasions that are not associated with antenna switching by the UE; 
 receiving an indication of a random access channel occasion, included in the first set of random access channel occasions or the second set of random access channel occasions, associated with the PRACH sequence; and 
 determining whether to perform antenna switching when transmitting the PRACH sequence based at least in part on whether the random access channel occasion is included in the first set of random access channel occasions or the second set of random access channel occasions. 
 
     
     
       24. The method of  claim 14 , wherein receiving the random access channel configuration comprises:
 receiving an indication of the PRACH format from the one or more PRACH formats, wherein the PRACH format includes one or more repetition groups and an indication that antenna switching is to be used by the UE when transmitting the PRACH sequence, wherein each repetition group of the one or more repetition groups includes: one or more repetitions of the PRACH sequence, and a cyclic prefix. 
 
     
     
       25. The method of  claim 24 , wherein receiving the indication of the PRACH format comprises at least one of:
 receiving an indication that the UE is to perform an antenna switching procedure at an end of at least one of the one or more repetition groups, or 
 receiving an indication of at least one of:
 a starting time of each repetition group included in the one or more repetition groups, wherein the starting time is based at least in part on an amount of time associated with an antenna switching capability of the UE, or 
 an indication of a time gap between each repetition group included in the one or more repetition groups. 
 
 
     
     
       26. An apparatus for wireless communication, comprising:
 a memory comprising instructions; and 
 one or more processors configured to execute the instructions and cause the apparatus to:
 obtain an indication of resources reserved for the apparatus and to be used for a physical random access channel (PRACH) sequence; and 
 output for transmission, based at least in part on the indication of the reserved resources, the PRACH sequence in accordance with a transmission timing for the PRACH sequence. 
 
 
     
     
       27. The apparatus of  claim 26 , wherein the resources reserved for the apparatus include at least one of:
 time domain resources that occur prior to time domain resources to be used for the PRACH sequence, or 
 time domain resources that occur after the time domain resources to be used for the PRACH sequence. 
 
     
     
       28. A method of wireless communication performed at a user equipment (UE), comprising:
 receiving an indication of resources reserved for the UE and to be used for a physical random access channel (PRACH) sequence; and 
 transmitting, based at least in part on the indication of the resources, the PRACH sequence in accordance with a transmission timing for the PRACH sequence. 
 
     
     
       29. The method of  claim 28 , further comprising:
 identifying a first cyclic prefix duration based at least in part on a PRACH format of the PRACH sequence; and 
 modifying the first cyclic prefix duration by a factor to obtain a second cyclic prefix duration,
 wherein transmitting the PRACH sequence comprises transmitting the PRACH sequence with a cyclic prefix having the second cyclic prefix duration. 
 
 
     
     
       30. The apparatus of  claim 26 , further comprising at least one transceiver configured to receive the indication of resources to be used for the PRACH sequence and transmit the PRACH sequence in accordance with the transmission timing, wherein the apparatus is configured as a user equipment.